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  <div class="section" id="numpy-indices">
<h1>numpy.indices<a class="headerlink" href="#numpy-indices" title="Permalink to this headline">¶</a></h1>
<dl class="function">
<dt id="numpy.indices">
<code class="sig-prename descclassname">numpy.</code><code class="sig-name descname">indices</code><span class="sig-paren">(</span><em class="sig-param">dimensions</em>, <em class="sig-param">dtype=&lt;class 'int'&gt;</em>, <em class="sig-param">sparse=False</em><span class="sig-paren">)</span><a class="reference external" href="https://github.com/numpy/numpy/blob/v1.18.1/numpy/core/numeric.py#L1622-L1722"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#numpy.indices" title="Permalink to this definition">¶</a></dt>
<dd><p>Return an array representing the indices of a grid.</p>
<p>Compute an array where the subarrays contain index values 0, 1, …
varying only along the corresponding axis.</p>
<dl class="field-list">
<dt class="field-odd">Parameters</dt>
<dd class="field-odd"><dl>
<dt><strong>dimensions</strong><span class="classifier">sequence of ints</span></dt><dd><p>The shape of the grid.</p>
</dd>
<dt><strong>dtype</strong><span class="classifier">dtype, optional</span></dt><dd><p>Data type of the result.</p>
</dd>
<dt><strong>sparse</strong><span class="classifier">boolean, optional</span></dt><dd><p>Return a sparse representation of the grid instead of a dense
representation. Default is False.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 1.17.</span></p>
</div>
</dd>
</dl>
</dd>
<dt class="field-even">Returns</dt>
<dd class="field-even"><dl class="simple">
<dt><strong>grid</strong><span class="classifier">one ndarray or tuple of ndarrays</span></dt><dd><dl class="simple">
<dt>If sparse is False:</dt><dd><p>Returns one array of grid indices,
<code class="docutils literal notranslate"><span class="pre">grid.shape</span> <span class="pre">=</span> <span class="pre">(len(dimensions),)</span> <span class="pre">+</span> <span class="pre">tuple(dimensions)</span></code>.</p>
</dd>
<dt>If sparse is True:</dt><dd><p>Returns a tuple of arrays, with
<code class="docutils literal notranslate"><span class="pre">grid[i].shape</span> <span class="pre">=</span> <span class="pre">(1,</span> <span class="pre">...,</span> <span class="pre">1,</span> <span class="pre">dimensions[i],</span> <span class="pre">1,</span> <span class="pre">...,</span> <span class="pre">1)</span></code> with
dimensions[i] in the ith place</p>
</dd>
</dl>
</dd>
</dl>
</dd>
</dl>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="numpy.mgrid.html#numpy.mgrid" title="numpy.mgrid"><code class="xref py py-obj docutils literal notranslate"><span class="pre">mgrid</span></code></a>, <a class="reference internal" href="numpy.ogrid.html#numpy.ogrid" title="numpy.ogrid"><code class="xref py py-obj docutils literal notranslate"><span class="pre">ogrid</span></code></a>, <a class="reference internal" href="numpy.meshgrid.html#numpy.meshgrid" title="numpy.meshgrid"><code class="xref py py-obj docutils literal notranslate"><span class="pre">meshgrid</span></code></a></p>
</div>
<p class="rubric">Notes</p>
<p>The output shape in the dense case is obtained by prepending the number
of dimensions in front of the tuple of dimensions, i.e. if <em class="xref py py-obj">dimensions</em>
is a tuple <code class="docutils literal notranslate"><span class="pre">(r0,</span> <span class="pre">...,</span> <span class="pre">rN-1)</span></code> of length <code class="docutils literal notranslate"><span class="pre">N</span></code>, the output shape is
<code class="docutils literal notranslate"><span class="pre">(N,</span> <span class="pre">r0,</span> <span class="pre">...,</span> <span class="pre">rN-1)</span></code>.</p>
<p>The subarrays <code class="docutils literal notranslate"><span class="pre">grid[k]</span></code> contains the N-D array of indices along the
<code class="docutils literal notranslate"><span class="pre">k-th</span></code> axis. Explicitly:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">grid</span><span class="p">[</span><span class="n">k</span><span class="p">,</span> <span class="n">i0</span><span class="p">,</span> <span class="n">i1</span><span class="p">,</span> <span class="o">...</span><span class="p">,</span> <span class="n">iN</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="n">ik</span>
</pre></div>
</div>
<p class="rubric">Examples</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">grid</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">indices</span><span class="p">((</span><span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">grid</span><span class="o">.</span><span class="n">shape</span>
<span class="go">(2, 2, 3)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">grid</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>        <span class="c1"># row indices</span>
<span class="go">array([[0, 0, 0],</span>
<span class="go">       [1, 1, 1]])</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">grid</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>        <span class="c1"># column indices</span>
<span class="go">array([[0, 1, 2],</span>
<span class="go">       [0, 1, 2]])</span>
</pre></div>
</div>
<p>The indices can be used as an index into an array.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">x</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">arange</span><span class="p">(</span><span class="mi">20</span><span class="p">)</span><span class="o">.</span><span class="n">reshape</span><span class="p">(</span><span class="mi">5</span><span class="p">,</span> <span class="mi">4</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">row</span><span class="p">,</span> <span class="n">col</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">indices</span><span class="p">((</span><span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">x</span><span class="p">[</span><span class="n">row</span><span class="p">,</span> <span class="n">col</span><span class="p">]</span>
<span class="go">array([[0, 1, 2],</span>
<span class="go">       [4, 5, 6]])</span>
</pre></div>
</div>
<p>Note that it would be more straightforward in the above example to
extract the required elements directly with <code class="docutils literal notranslate"><span class="pre">x[:2,</span> <span class="pre">:3]</span></code>.</p>
<p>If sparse is set to true, the grid will be returned in a sparse
representation.</p>
<div class="doctest highlight-default notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">i</span><span class="p">,</span> <span class="n">j</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">indices</span><span class="p">((</span><span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">),</span> <span class="n">sparse</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">i</span><span class="o">.</span><span class="n">shape</span>
<span class="go">(2, 1)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">j</span><span class="o">.</span><span class="n">shape</span>
<span class="go">(1, 3)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">i</span>        <span class="c1"># row indices</span>
<span class="go">array([[0],</span>
<span class="go">       [1]])</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">j</span>        <span class="c1"># column indices</span>
<span class="go">array([[0, 1, 2]])</span>
</pre></div>
</div>
</dd></dl>

</div>


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